The present invention relates to a micro actuator, and more particularly to improvements in a micro actuator in which the amount of translational displacement can be easily enlarged.
There are many micro actuators (hereinafter referred to as actuators) which are in a research-and-development stage, but the number of actuators which have reached the product stage is very small. This is conceivably due partly to the difficulty in the microminiturization of the actuators themselves. In such a situation, Japanese Patent Unexamined Publication No. Hei. 8-90477 is known as the conventional art of the actuator which discloses the basic configuration of a product.
Such an actuator is characterized by a drive mechanism in which the expanding and contracting displacement of a movable frame due to a piezoelectric element is converted to the opening and closing displacement of a U-shaped pair of gripper fingers through a swinging mechanism consisting of a hinge and levers, and there is an advantage in that the pair of gripper fingers exhibits equalized opening and closing behavior with respect to an object to be gripped.
With the above-described conventional actuator, however, to utilize the expanding and contracting displacement of the piezoelectric element as the displacement for actuating the gripper, a mechanism for enlarging the displacement must be provided, so that the structure has been complex. For example, since the expanding and contracting displacement of the piezoelectric element is on the order of nanometers, there has been a problem in that a mechanism for enlargement by a factor of several hundreds is required to obtain an opening and closing displacement of even several hundred microns for the gripper fingers.
The invention has been made to overcome the above-described problems, and its object is to provide an actuator in which the amount of displacement of a distal end portion gets large on the basis of a slight amount of displacement of a driving section without using an enlarging mechanism.
To attain this object, the actuator according to a first aspect is characterized by comprising: a translationally driving section having a moving portion which is incorporated in a case and moves translationally; and a displacement enlarging member having one end portion connected to the moving portion of the translationally driving section and another end portion connected to the case, wherein as the one end portion is pulled on the basis of the translational movement, the displacement enlarging member is extended from the end portion and the one end portion more than an amount of the translational movement, and an amount of displacement of its common distal end is enlarged.
The actuator according to a second aspect is characterized by comprising: a translationally driving section having a moving portion which is incorporated in a case and moves translationally; and a displacement enlarging member including a common portion having a distal end in common, at least two side portions extending from the common portion and opposing each other, and an open portion which is located on a side away from the common portion and is open, wherein one end of the open portion is connected to the translationally driving section, another end of the open portion is connected to the case, and the distal end is subjected to enlarging displacement on the basis of the translational displacement of the translationally driving section.
The actuator according to a third aspect is characterized in that the displacement enlarging member exhibits a buckling phenomenon as the one end of the open portion is translationally displaced.
The actuator according to a fourth aspect is characterized in that the common portion of the displacement enlarging member has a secured portion in which distal end portions of the displacement enlarging member are secured together in a superposed manner.
The actuator according to a fifth aspect is characterized in that first and second displacement enlarging members are provided, and one ends of the open portions of the first and second displacement enlarging members are held in common and are connected to the translationally driving section.
The actuator according to a sixth aspect is characterized in that the shape of the displacement enlarging member is substantially V-shaped.
The actuator according to a seventh aspect is characterized in that a projecting portion which projects to an outside is provided on at least one of the side portions of the displacement enlarging member.
The actuator according to an eighth aspect is characterized in that, instead of the common portion having the distal end of the displacement enlarging member in common, the common portion is one having a vicinity of the distal end and a central portion of the displacement enlarging member in common.
The actuator according to a ninth aspect is characterized in that the translationally driving section is comprised of a motor having a shaft and a converting section for converting the rotation of the shaft to translational displacement, and wherein there are provided a connecting section for connecting together the converting section and one end of the displacement enlarging member, and a fixing section provided in the case for fixing another end of the displacement enlarging member, the connecting section being also accommodated in the case.
The actuator according to a 10th aspect is characterized in that the converting section is comprised of a nut with an internal thread formed therein and a transmitting member threadedly engaged with the nut and connected to the shaft, and wherein the length of threaded portions of the nut, the shaft or the nut, and the transmitting member is less than or equal to a maximum value of the amount of translational displacement.
The actuator according to an 11th aspect is characterized in that a substantially circularly formed circular portion is provided at one end portion of the open portion of the displacement enlarging member, and a groove with which the circular portion is engaged is provided in the connecting section.
The actuator according to a 12th aspect is characterized in that the nut has the shape of a substantially quadrangular prism, and a guide portion for guiding the nut as an outer surface of the nut is slidingly engaged therewith has opposite ends which are substantially semicircular.